The present invention relates to apparatus for forming a lens pattern and in particular to a fixture for moving a pattern and eyeglass frame relatively in two dimensions.
A known lens former has a base with a wall against which an eyeglass frame can be placed. A lens pattern is placed underneath the eyeglass frame and a scribing tool is used to trace the outline of the opening of the eyeglass frame. Thereafter, the lens pattern can be cut to the scribed size matching the opening of the eyeglass frame. Once so cut, the pattern can be placed in an edging machine which can be used to grind the edge of the lens so its outline matches that of the lens pattern and the opening in the eyeglass frame. A disadvantage with this equipment is that there is no convenient way of centering the lens pattern within the eyeglass frame. If the pattern and the eyeglass frame both rest against the wall on the base, it will be difficult to center the pattern.
It is also known to place an eyeglass frame on a base having two perpendicularly movable walls. These walls can be used to move the eyeglass frame in two dimensions and thereby place it in a desired position over a predetermined position on the base. Fixtures of this type have been used, however, to mold a lens pattern rather than scribe an outline on a pattern. Accordingly, this technique requires elaborate procedures for establishing a form and casting a pattern. In addition, the procedure of moving a wall adds inaccuracies since a relatively long wall needs to be moved without changing its angular relationship with respect to the other movable wall.
Accordingly, there is a need for an improved apparatus for forming a lens pattern which enables the eyeglass frame and lens pattern to be moved relatively in two dimensions while keeping an accurately fixed angular relationship among the components.